otner siae or the snouiuer is tappeu wau we poinieu sewing instrument (25). The instrument is rotated from shoulder to shoulder until the bladevent is seated to its proper depth.

Caution: Continue securing (26) the untapped post even after the implant enters the crest. The implant should not rock in its site, and can be easily knocked above the crest if a finger does not trap it there.

Caution: When using a modified, notched screwdriver (27) to insert a bladevent, do not approach the crest too closely with the implement. It can injure crestal bone, and should be substituted at this state with a pointed inserting tool.

Frequently when the posts have been acutely angled and the socket entrance is lingually offset, it is impossible to correctly seat the implant—with all faces of the bottom of a post resting on alveolar bone—without additional remodeling of the crest. The neck and part of the shoulder may be exposed labially (28), al-though lingually it contacts bone (28a).

To properly seat the posts, it is necessary to countersink them; that is, to cut a depression in the higher—or lingual—side of the

bone (29) just beneath the posts.

The 700 XL bur is used, with the water coolant particularly essential because of close proximity to the metal bladevent (30). Only that bone interfering with proper seating is removed (30A). This allows the buccal portion of the blade, shoulder and neck to be buried as deeply as the lingual side, thus giving the bladevent additional protection against tongue thrusts (31). It is neither necessary nor desirable to extensively reshape the crest to correctly seat the posts. Countersinking is adequate.

After removing bone for countersinking, the posts may not touch the crest (32) because the groove is now too shallow. The implant is removed, and the groove deepened to properly seat the implant (33).

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